Stenocyamops luteus, Grimaldi, 2009

Grimaldi, David A., 2009, The Asteioinea of Fiji (Insecta: Diptera: Periscelididae, Asteiidae, Xenasteiidae), American Museum Novitates 3671, pp. 1-60 : 28-29

Stenocyamops luteus , new species

Figures 3 , 4 , 16 , 17 , 18 , 21

DIAGNOSIS: Head and thorax almost entirely yellow; band of silvery microtomentum on cheeks very narrow, barely noticeable; 3–4 fine anepisternal setae; diffuse, light brown band across dorsal portion of pleura; tergites III, IV dark brown (sometimes VII + VIII in males, VII in females). Male genitalia with ventral lobes of cerci having apices rounded, not pointed; surstylus nearly straight (vs. scimitar shaped), with an apical tooth; hypandrium without pair of phragmata.

DESCRIPTION: ThL 5 0.64 mm. Differing from S. robustus most obviously in body coloration: Head: Frons, face, clypeus and proboscis, vertex, postgena, and ground color of cheeks are bright yellow; area between ocelli dark brown, ocelli yellowish to red; eyes dark purplish; cheeks with very thin band of silvery-reflective microtomentum (slightly broader in females). Antennal pedicel and basal flagellomere light yellowish ochre; arista blackish brown. Thorax: Dorsal portion of scutum and scutellum entirely yellow, pleura mostly yellow, except light brown infuscation in ground color of anepisternum, dorsal portion of anepimeron, on katatergite and anatergite, and membrane at base of wing; anepisternum largely covered with silveryreflective microtomentum; halter base slightly infuscate, bulb white. Legs light yellow, hind tarsi whitish. Wing hyaline. Abdomen with tergites III, IV dark brown in both sexes (sometimes also VII + VIII in males, and VII in females). Setae on head blackish brown; setae on thorax and legs lighter.

Other features similar to S. robustus , with differences as follows: Arista with 6–7 dorsal and 2 ventral branches (plus terminal fork); basal dorsal branches less crowded near base of aristal trunk, basal branches in line with more terminal ones. Pseudovibrissae stout, projecting forward and slightly divergent; bases separated by distance approximately equal to 2–3X diameter of base socket. Ventral to pseudovibrissae are 7 pairs oral setae; pair closest to pseudovibrissae project forward and curve slightly laterad; others project laterad and curve slightly ventrad. Thorax: much less deep than in S. robusta , depth approximately 0.7X the length in lateral view. (Meso-) scutum with single row of 5 long acrostichals, extended posteriad to level of dorsocentrals; anterior dorsocentral approximately 0.4X length of posterior one (supraalar seta absent?). Anepisternum with row of 3–4 fine setae on posterior margin. Coxae and mesosternum with pilosity of long, very fine, golden setae. Forefemur with long, fine, erect setae, row of 3–4 long, stiff setae on ventrolateral surface. Midtibia with long, stout, apical spur, length about 0.4X that of basitarsomere. Wing: hyaline, fairly broad (W/L 5 0.41), with dorsal surface of vein R 1 without fine setae. Sc incomplete, cross veins br-m and dm-cu absent, other cross veins well separated (L r-m / distance between dr-m and dm-cu 0.20). Vein A 1 +CuA 2 present, with an abrupt ending; vein A absent; alula highly reduced, anal lobe virtually lost. Male Terminalia: Paired structures and hypandrium symmetrical. Epandrium setulose, deep. Dorsal half of cerci extensive, membranous, with numerous microtrichia; cerci ventrally with pair of pendulous, setulose, rounded lobes, each bearing ca. 5 setae preapically. Surstylus setulose, nearly straight, curved slightly preapically, with setulae near apex and small apical tooth. Hypandrium reduced into two lateral lobes; median portion narrow, with fine gap; no phragmata. Aedeagus short, bulbous, spiculed, having several lightly sclerotized strips (as figured). Female terminalia: Tergite VI simple, not fused to sternite, with pair of sternites near lateral margin; sclerites of segment VII fused into syntergosternite, bearing pair of lateral spiracles; tVIII small, narrow. Two spermathecae, ovoid, not spherical; heavily sclerotized; lying beneath level where tVI and VII meet.

TYPES: Holotype, male (not dissected), Viti Levu : VII.11.08, Namosi Rd. , 200 m., 18 ° 069110S, 178 ° 109290E, in rolled banana leaves, D. Grimaldi coll. In AMNH. Paratypes: Viti Levu , VII.9.08, Nakobalevu Rd. , 394 m., 18 ° 039310S, 178 ° 249550E, rolled leaves, D. Grimaldi, 2 females (one numbered, no. 34), 2 males (no. 41, dissected). Vanua Levu : VII.9.08, road up Mt. Ndulaikoro , 1000 m, in rolled leaves wild ginger, D. Grimaldi (2 males) ; VII.2.08, 163 ° 29210S, 179 ° 329500E, 402 m, D. Grimaldi, in rolled banana leaves. In AMNH. Taveuni : Cakadrove Prov., 5.6 km SE of Tavuki Village, Malaise, rainforest 31.X– 14.XI.02, Schlinger & Tokota’a FJTA8 a_MO1_ 06, 216.843 °, 2179.965 °, 1187 m, FBA056963 (female). In BPBM.

ETYMOLOGY: From the Latin, luteus , for ‘‘yellow.’’

Figures

Fig. 3. Abdominal coloration of select Fiji Periscelididae, dorsal views (to same scale). A. Stenocyamops vittatus, n. sp. B. Stenocyamops robustus. C. Stenocyamops luteus, n. sp. D, E: Stenomicra tokotaii, male (D) and apex of female abdomen (E). F, G: Stenomicra distincta, male (F) and apex of female abdomen (G).

Fig. 4. A–E: Terminal abdominal segments and syntergosternites of male Periscelididae (ventral views, not to same scale). A. Stenocyamops robustus. B. Stenocyamops luteus/pseudoluteus. C. Stenomicra distincta. D. Stenomicra distinctipennis. E. Stenomicra castanea. F–H: Thoraces (dorsal view) of select Fiji Stenomicra (to the same scale). F. S. brunnea. G. S. xoutha. H. S. sylpha.

Fig. 16. Heads of Fiji Stenocyamops, oblique frontal views. A. S. robustus (spcm. 28). B. S. luteus (spcm. 29). To same scale. Differentiation in facet size is modest, and silvery microtomentum is restricted to the cheeks.

Fig. 17. Wings of Fiji Periscelididae. A–C: Stenocyamops. A, B. S. luteus, entire (B) and detail of base

Fig. 18. Male terminalia of Stenocyamops luteus (spcm. 41). A. Epandrial complex with aedeagus, posterior view. B. Hypandrium, aedeagal apodeme, and aedeagus, anterior view. To the same scale.

Fig. 21. Female terminalia of Fiji Stenocyamops, dorsal views (all to the same scale). A. S. luteus (spcm. 34). B. S. vittatus (spcm. 33). C. S. robustus (spcm. 31). Spermathecae are heavily sclerotized; the last pair of spiracles occur in the lateral margins of syntergosternite VII.